Climate change resulting in increased temperature could impact crop pest insect population in several complex ways. Increased temperature can potentially affect insect survival, development, geographic range and population size.
Temperature can impact insect physiology and development directly or indirectly through the physiology or existence of hosts. Depending on the development strategy of an insect species, temperature can exert different effects.
Reproductive biology of an insect may be affected both positively and negatively. Climate, temperature and precipitation in particular, have a very strong influence on the development, reproduction and survival of insect pests and as a result it is highly likely that these organisms will be affected by any change in climate.
Warmer temperatures in temperate climates will result in more types and higher populations of insects. Some insects like arctic moths take several years to complete one lifecycle.
Some crop pests are ‘stop’ and ‘go’ developers in relation to temperature —they develop more rapidly during periods of time with suitable temperatures. Increased temperatures will accelerate the development of these types of insects, possibly resulting in more generations per year.
Insects that spend important part of their life histories in the soil may be more gradually affected by temperature changes than those that are above ground simply because the soil provides an insulating medium that will tend to buffer temperature changes more than the air.
Rise in temperature in winter may help to continue the lifecycle of some pests. Lower winter mortality of insects due to warmer winter temperature could be important in increasing insect populations.
Insect species diversity for a particular area tends to decrease with higher latitude and altitude indicating that rising temperature could result in more insect species attacking more hosts in temperate climates.
(Dr.D. N. Kambrekar, Scientist (Agricultural Entomology), Regional Agricultural Research Station, PB. No. 18, Vijayapur-586 101, Karnataka, email: kambrekardn@uasd.in Phone : 08352-230568.)
